›something that controls what you can do by keeping you within particular limits: The constraint of distribution costs remains the severest of all.budget/financial, etc. constraintsThis growth in revenue may soften the government's budget constraints and allow it to increase public spending.big/major/serious constraintThey believe that the new legislation will remove a major constraint to economic expansion.a constraint on/to sthThe cost of capital is an important constraint on business activity.place/put a constraint on sthSome external factors placed constraints on the scope of the work that could be undertaken.Among those conditions was a five-year time constraint. (= time limit)